1. Field of the Invention
The present invention relates to a color copier. More particularly, the invention is concerned with a desktop color copier which can be used on a stand.
2. Description of the Related Art
It is desired to provide a space saving office device such as a copier, printer, or facsimile machine in order to minimize the amount of space occupied by the office device. Considering transportation of the office device, it is also desired to construct the office device to have measurements which are smaller than the entrance of an elevator.
In order to satisfy the aforementioned demand, a desktop black and white copier has been put on the market. The desktop copier usually can be used on a stand and therefore the measurements, especially the height, are small. It is desirable for the height of the desktop copier which is on the stand to be about 950 mm in view of the operation of the copier. It is also desirable that a desktop color copier be put on the market in order to satisfy demand. However, it is very difficult to manufacture a desktop color copier because color image forming devices, at least three developing devices and an intermediate transfer device which are not necessary for the black and white copier are necessary for a color copier, and therefore it is very difficult to provide a small desktop color copier. As proof of that, a desktop color copier has not been put on the market.
Further, the color copier has two or more paper feed devices since the color copier has more functions than the white and black copier. As a result, the color copier becomes large-size and therefore the desktop color copier cannot be built.
In view of improvement of efficiency of design and cost-efficiency, it is desired to reduce the size of the color copier. Namely, in order to improve efficiency of design and reduce the cost, it is essential to use common parts among different copiers. In order to use common parts, it is essential to use a common frame which determines the size of the copier for both the black and white copier and the color copier.
However, image forming devices, at least three developing devices and an intermediate transfer device, which are not necessary for the black and white copier are necessary for the color copier and therefore, the size of the color copier is larger than that of the black and white copier. As a result, it is impossible to use common parts, especially a common frame, for both the color copier and the black and white copier.
Accordingly, one object of this invention is to provide a novel color copier which can solve the aforementioned drawbacks. A further object of the present invention is to provide a color copier which can be used on a stand.
In order to achieve the above-mentioned objects, according to the present invention, a color image forming apparatus for forming a toner image on a sheet of paper includes an image carrier for sequentially forming toner images of respective colors thereon, a charger for charging the image carrier, an exposing device for exposing the charged carrier and forming electrostatic latent images of respective colors on the image carrier, and a revolving type developing device which is rotatively supported in the color image forming apparatus.
The revolving type developing device includes a plurality of color developing devices, each of which includes a developing unit for developing a toner image on the image carrier when the developing unit faces the image carrier and a toner supply unit for supplying toner to the developing unit. The external shape of the revolving type developing device is cylinder.
The color image forming apparatus further includes an intermediate transfer belt to which the toner images are sequentially transferred one above the other, a primary transferring charger for sequentially transferring the toner images from the image carrier to the intermediate transfer belt, thereby forming a composite toner image on the intermediate transfer belt, at least one paper feed tray for storing sheets of paper and feeding a sheet of paper. There is also a secondary image transferring charger for transferring the composite toner images from the intermediate transfer belt to the sheet of paper which is fed from the paper feed tray, and a fixing device for fixing the toner image on the sheet of paper. The color image forming apparatus is usually used when the color image forming apparatus is on a stand.
Other objects and aspects of the present invention will become apparent herein.